This research concerns the chemistry of enzyme models involving aminoalkylphosphonic acids, i.e., amino acids containing a carbon- phosphorus bond, and is aimed at establishing the effect of the phosphonate group on the known metabolic pathways involving the naturally-occurring aminocarboxylic acids. Little is known regarding the properties of these aminophosphonates, although several have been found in marine invertebrates and in man. The program involves: 1) investigation of Vitamin B6 models; 2) study of metal-catalyzed demethylation reactions; 3) synthesis and study of some simple phosphonopeptides and their metal chelates. The structure and stereochemistry of pyridoxal-aminoalkylphosphonate Schiff bases, as well as the kinetics and mechanism of their transamination, racemization, and phosphonate elimination reactions will be determined in the presence and absence of metal ions. Enzymic demethylation of tertiary aminoalkylphosphonates and the metal-catalyzed rearrangement of their corresponding N-oxides will be explored. Two classes of phosphonopeptides will be synthesized, and their metal binding properties will be compared with those of their aminocarboxylic counterparts.